Multifilament light



March 26, 1968v P. c. DEMARET ET AL MULTIFILAMENT LIGHT Filed May 6, 1966 INVENTORS Kate. Kmu Svd HKT H-MARQH ATTORNEY United States Patent Ofifice 3,375,394 Patented Mar. 26, 1968 3,375,394 MULTIFILAMENT LIGHT Philip C. Demarest, Pine Brook, andiKarl Karlson, Wallington, N.J., assignors to Ohme'ga Laboratories, Pine Brook, N.J., a corporation of New Jersey.

Filed May 6, 1966, Ser. No. 548,192 4 Claims. (Cl. 313-316) This invention relates to a light having several filaments all connected in parallel between two conductive walls that form part of the external wall structure of the light.

In medical instruments, dental drills and certain other devices it is desirable to have a highdegree of illumination concentrated on a small area close to the device so that the doctor, dentist or operator of the device can see this area clearly. If the illumination comes from external sources, it is likely to be interfered with by shadows from the operators hands or the devices being used.

In addition to a relatively high intensity light, it is desirable that the light not require a large amount of electric power which would necessitate heavy conductors and it is also desirable that the light be relatively sturdy and have a multiplicity of filaments connected in parallel so that if one burns out the light will not be rendered useless.

It is one of the principal objects of the present invention to provide a light source having a multiplicity of parallel-connected filaments extending between two metal walls that are part of the external wall Structure of the h light. Other objects are to provide an annular light source having a central hole through which a drill or other mechanical device may pass or which may surround an optical axis. Still further objects will become apparent from the following specification together with the drawings in which:

FIG. 1 is a plan view of a light constructed according to the invention;

FIG. 2 is a cross-sectional view of thelight of FIG. 1;

and

FIGS. 3 and 4 illustrate two applications of the light of FIGS. 1 and 2.

The light of the present invention is shown in greatly enlarged form in FIG. 1 and is there;. seen to include a conductive inner cylinder 11 and a conductive outer cylinder 12 concentric with the inner cylinder, and a plurality of fine conductive filaments connectedgbetween the inner anl outer cylinder to form a multippinted star. The filaments may be either skip wound or continuously wound and may be appropriately spot welded to space points on both the inner and outer cylinders 11 and 12, and the cylinders are preferably metal and form part of the external wall structure of the light.

FIG. 2 shows a cross-sectional view of the light of FIG. 1 and illustrates an embodiment in which the inner cylinder 11 has an integral radially extending flange 14 at one end. One end of the metal outer cylinder 12 is joined to the outer perimeter of the flange 14 by means of a suitable insulating seal such as a thin layer of glass 16 which is hermetically sealed both to the cylinder 12 and to the flange 14. At the other ends of both the inner cylinder 11 and the outer cylinder 12 there is a substantially transparent glass faceplate 17, here shown in the form of an annulus that covers only the annular space between the inner cylinder 11 and the outer cylinder 12, although in other embodiments, the faceplate 17 i could be a disc without a central opening. As may be seen in FIG. 2' the sections of the filament 13 extend substantially directly'between the cylinder 11 and the cylinder .12 and about midway along the length of the cylinder 12. With the mechanical arrangements of the flange 14 and the cylinder 12 it is possible to provide simple electrical terminals 18 and 19 thereto through which electrical current may be supplied to the individual sections of the filament 13 since the cylinder 12 is insulated from the cylinder 11 with its integral flange 14 by the thin glass sealing layer 16.

While the cylinders 11 and 12 are shown as sections of right circular cylinders, they may have other configurations. For example, they may be sections of rectangular cylinders or of even more arbitrary shapes as long as one is insulated from the other and the filament extends back and forth from one cylinder to the other to form a mulitplicity of conductive filaments.

The advantage of having a multiplicity of filaments is that if any one filament breaks or burns out the utility of the light will not be completely destroyed, for the remainder of the filaments will normally remain operative and only a relatively small percentage of the total illumination will be lost by the breakage of the one strand. FIG. 3 shows an application of the light of FIG. 1 in which the light is used to provide illumination along the directions indicated by the arrow rays 21, and the central opening in the light permits reflected rays to .return from the illuminated to the eye of a viewer.

In this case it is advantageous to have the flange 14 made of metal so that no light will be directed against the eye of the viewer, while at the same time the overall configuration of the light is such as to give the maximum possible volumetric efiiciency, since there is no separate base structure required for this light.

By making the filament 13 of extremely fine wire, the loss of heat from the filament to the cylinder 11 and 12 is minimal and this helps the lamp to operate at a low power. The gap between the cylinders 11 and 12 should also be small, and these factors plus the provision of many filaments in parallel provide a bright light that does not get very hot, which permits the light to be used quite close to delicate objects, as is frequently required in medical and dental examinations.

FIG. 4 shows the advantage of the central aperture through the light when it is desired to use the light in conjunction with a rotating mechanical structure such as a dental drill 22. The light of the present invention may be attached quite readily to the end of the support structure of a dental drill and the bit itself may extend directly through the central opening in the inner cylinder 11. By virtue of the structure of the present light, illumination is provided directly on the surface of the tooth, or other object, being drilled.

While this invention has been described in terms of a specific embodiment, it will be understood by those skilled in the art that modifications may be made therein within the scope of the following claims.

What is claimed is:

1. A light having first and second spaced conductive walls; two end walls joining the spaced walls, one of said end walls at each end of said spaced walls, respectively; and a plurality of groups of filaments, stretching from one of said walls to the other and being joined at each of said walls.

2. The invention as defined in claim 1 in which said first wall is in the form of a right circular cylinder'and said second wall is in the form of a right circular cylinder spaced outside of said first right circular cylinder and said filaments are arranged in the form of a rnulti-pointed star with the outer points being afiixed to said outer cylinder and the inner points being affixed to said inner cylinder.

3. The invention as defined in claim 2 in which said inner cylinder has a radially outwardly extending flange at one end thereof joined to one end of said outer cylinder; and an insulating medium joining said flange to said outer cylinder.

4. The invention as defined in claim 1 in which said filaments comprise sections of a single-filament joined alternately to said first and second conductive walls.

References Cited UNITED STATES PATENTS 3,286,118 11/1966 Vause et a1 3l3318 10 JOHN w. HUCKERT, Primary Examiner.

I. R. SHEWMAKER, Assistant Examiner. 

1. A LIGHT HAVING FIRST AND SECOND SPACED CONDUCTIVE WALLS; TWO END WALLS JOINING THE SPACED WALLS, ONE OF SAID END WALLS AT EACH END OF SAID SPACED WALLS, RESPECTIVELY; AND A PLURALITY OF GROUPS OF FILAMENTS, STRETCHING FROM ONE OF SAID WALLS TO THE OTHER AND BEING JOINED AT EACH OF SAID WALLS. 